A software-defined radio is a radio communication system whose channel waveforms are defined in software. That is, waveforms are generated as sampled digital signals, converted from digital to analog via a wideband Digital to Analog Converter (DAC) and then possibly upconverted from IF to RF. Likewise, the receiver employs a wideband Analog to Digital Converter (ADC) that captures all of the channels of the software radio node. The receiver then extracts, downconverts and demodulates the channel waveform using software on a general purpose processor. Thus, a variety of different waveforms and communication protocols can be supported in software. However, as operational complexity increases, the power demand also increases. This is of particular concern in battery-powered radios.
To transmit over a wide range of frequencies, the amplifier powering the antenna needs to handle a variety of antenna load impedances. The amplifier is typically designed to accommodate all of the anticipated load impedances. In other words, the amplifier is designed to meet the worst case scenario, thereby resulting in sub-optimum efficiency when the load impedance is good. Therefore, it is desirable to adjust the operating parameters of the amplifier to match the load impedances, thereby improving amplifier efficiency and reducing power consumption.
The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.